             [:div.auction-end-time
              [auction-end-time-date-picker
               {:selected end-time
-               :on-change #(swap! form-data assoc :auction-offering/end-time %)}]])
+               :on-change #(swap! form-data assoc
+                             :auction-offering/end-time %
+                             :auction-offering/extension-duration
+                               (min extension-duration
+                                    (max-extension-duration-hours @now %)))}]])
           (when (and (or auction? (not editing?))
                      (not editing?))
             [:div.info

                                 (not (or (not auction?)
                                          valid-min-bid-increase?))
                                 (and auction?
                                      (t/after? @now (from-date (.toDate (js/moment end-time))))))]
        [:div
         [:div.grid.offering-form.submit-footer
          [:div.name

          (when auction?
            [:div.duration-slider
             [offering-extension-duration-slider
              (max-extension-duration-hours @now end-time)
              {:value extension-duration
               :on-change #(swap! form-data assoc :auction-offering/extension-duration (aget % "target" "value"))}]])
          (when (and (or auction? (not editing?))
